var WebRtcStreamer = (function() {
  /**
   * Interface with WebRTC-streamer API
   * @constructor
   * @param {string} videoElement - id of the video element tag
   * @param {string} srvurl -  url of webrtc-streamer (default is current location)
   */
  var WebRtcStreamer = function WebRtcStreamer(videoElement, srvurl) {
    if (typeof videoElement === 'string') {
      this.videoElement = document.getElementById(videoElement);
    } else {
      this.videoElement = videoElement;
    }
    this.srvurl =
      srvurl ||
      location.protocol +
        '//' +
        window.location.hostname +
        ':' +
        window.location.port;
    this.pc = null;

    this.pcOptions = { optional: [{ DtlsSrtpKeyAgreement: true }] };

    this.mediaConstraints = {
      offerToReceiveAudio: true,
      offerToReceiveVideo: true,
    };

    this.iceServers = null;
    this.earlyCandidates = [];
  };

  WebRtcStreamer.prototype._handleHttpErrors = function(response) {
    if (!response.ok) {
      throw Error(response.statusText);
    }
    return response;
  };

  /**
   * Connect a WebRTC Stream to videoElement
   * @param {string} videourl - id of WebRTC video stream
   * @param {string} audiourl - id of WebRTC audio stream
   * @param {string} options -  options of WebRTC call
   * @param {string} stream  -  local stream to send
   */
  WebRtcStreamer.prototype.connect = function(
    videourl,
    audiourl,
    options,
    localstream
  ) {
    this.disconnect();

    // getIceServers is not already received
    if (!this.iceServers) {
      //   console.log('Get IceServers');

      fetch(this.srvurl + '/api/getIceServers')
        .then(this._handleHttpErrors)
        .then((response) => response.json())
        .then((response) =>
          this.onReceiveGetIceServers.call(
            this,
            response,
            videourl,
            audiourl,
            options,
            localstream
          )
        )
        .catch((error) => '推流请求报错');
      //   .catch((error) => this.onError('getIceServers ' + error));
    } else {
      this.onReceiveGetIceServers(
        this.iceServers,
        videourl,
        audiourl,
        options,
        localstream
      );
    }
  };

  /**
   * Disconnect a WebRTC Stream and clear videoElement source
   */
  WebRtcStreamer.prototype.disconnect = function() {
    if (this.videoElement) {
      this.videoElement.src = '';
    }
    if (this.pc) {
      fetch(this.srvurl + '/api/hangup?peerid=' + this.pc.peerid)
        .then(this._handleHttpErrors)
        .catch((error) => this.onError('hangup ' + error));

      try {
        this.pc.close();
      } catch (e) {
        // console.log('Failure close peer connection:' + e);
      }
      this.pc = null;
    }
  };

  /*
   * GetIceServers callback
   */
  WebRtcStreamer.prototype.onReceiveGetIceServers = function(
    iceServers,
    videourl,
    audiourl,
    options,
    stream
  ) {
    this.iceServers = iceServers;
    this.pcConfig = iceServers || { iceServers: [] };
    try {
      this.createPeerConnection();

      var callurl =
        this.srvurl +
        '/api/call?peerid=' +
        this.pc.peerid +
        '&url=' +
        encodeURIComponent(videourl);
      if (audiourl) {
        callurl += '&audiourl=' + encodeURIComponent(audiourl);
      }
      if (options) {
        callurl += '&options=' + encodeURIComponent(options);
      }

      if (stream) {
        this.pc.addStream(stream);
      }

      // clear early candidates
      this.earlyCandidates.length = 0;

      // create Offer
      var bind = this;
      this.pc.createOffer(this.mediaConstraints).then(
        function(sessionDescription) {
          //   console.log('Create offer:' + JSON.stringify(sessionDescription));

          bind.pc.setLocalDescription(
            sessionDescription,
            function() {
              fetch(callurl, {
                method: 'POST',
                body: JSON.stringify(sessionDescription),
              })
                .then(bind._handleHttpErrors)
                .then((response) => response.json())
                .catch((error) => bind.onError('call ' + error))
                .then((response) => bind.onReceiveCall.call(bind, response))
                .catch((error) => bind.onError('call ' + error));
            },
            function(error) {
              //   console.log('setLocalDescription error:' + JSON.stringify(error));
            }
          );
        },
        function(error) {
          alert('Create offer error:' + JSON.stringify(error));
        }
      );
    } catch (e) {
      this.disconnect();
      alert('connect error: ' + e);
    }
  };

  WebRtcStreamer.prototype.getIceCandidate = function() {
    fetch(this.srvurl + '/api/getIceCandidate?peerid=' + this.pc.peerid)
      .then(this._handleHttpErrors)
      .then((response) => response.json())
      .then((response) => this.onReceiveCandidate.call(this, response))
      .catch((error) => bind.onError('getIceCandidate ' + error));
  };

  /*
   * create RTCPeerConnection
   */
  WebRtcStreamer.prototype.createPeerConnection = function() {
    // console.log(
    //   'createPeerConnection  config: ' +
    //     JSON.stringify(this.pcConfig) +
    //     ' option:' +
    //     JSON.stringify(this.pcOptions)
    // );
    this.pc = new RTCPeerConnection(this.pcConfig, this.pcOptions);
    var pc = this.pc;
    pc.peerid = Math.random();

    var bind = this;
    pc.onicecandidate = function(evt) {
      bind.onIceCandidate.call(bind, evt);
    };
    pc.onaddstream = function(evt) {
      bind.onAddStream.call(bind, evt);
    };
    pc.oniceconnectionstatechange = function(evt) {
      //   console.log(
      //     'oniceconnectionstatechange  state: ' + pc.iceConnectionState
      //   );
      if (bind.videoElement) {
        if (pc.iceConnectionState === 'connected') {
          bind.videoElement.style.opacity = '1.0';
        } else if (pc.iceConnectionState === 'disconnected') {
          bind.videoElement.style.opacity = '0.25';
        } else if (
          pc.iceConnectionState === 'failed' ||
          pc.iceConnectionState === 'closed'
        ) {
          bind.videoElement.style.opacity = '0.5';
        } else if (pc.iceConnectionState === 'new') {
          bind.getIceCandidate.call(bind);
        }
      }
    };
    pc.ondatachannel = function(evt) {
      //   console.log('remote datachannel created:' + JSON.stringify(evt));

      evt.channel.onopen = function() {
        // console.log('remote datachannel open');
        this.send('remote channel openned');
      };
      evt.channel.onmessage = function(event) {
        // console.log('remote datachannel recv:' + JSON.stringify(event.data));
      };
    };
    pc.onicegatheringstatechange = function() {
      if (pc.iceGatheringState === 'complete') {
        const recvs = pc.getReceivers();

        recvs.forEach((recv) => {
          if (recv.track && recv.track.kind === 'video') {
            // console.log("codecs:" + JSON.stringify(recv.getParameters().codecs))
          }
        });
      }
    };

    try {
      var dataChannel = pc.createDataChannel('ClientDataChannel');
      dataChannel.onopen = function() {
        // console.log('local datachannel open');
        this.send('local channel openned');
      };
      dataChannel.onmessage = function(evt) {
        // console.log('local datachannel recv:' + JSON.stringify(evt.data));
      };
    } catch (e) {
      //   console.log('Cannor create datachannel error: ' + e);
    }

    // console.log(
    //   'Created RTCPeerConnnection with config: ' +
    //     JSON.stringify(this.pcConfig) +
    //     'option:' +
    //     JSON.stringify(this.pcOptions)
    // );
    return pc;
  };

  /*
   * RTCPeerConnection IceCandidate callback
   */
  WebRtcStreamer.prototype.onIceCandidate = function(event) {
    if (event.candidate) {
      if (this.pc.currentRemoteDescription) {
        this.addIceCandidate(this.pc.peerid, event.candidate);
      } else {
        this.earlyCandidates.push(event.candidate);
      }
    } else {
      //   console.log('End of candidates.');
    }
  };

  WebRtcStreamer.prototype.addIceCandidate = function(peerid, candidate) {
    fetch(this.srvurl + '/api/addIceCandidate?peerid=' + peerid, {
      method: 'POST',
      body: JSON.stringify(candidate),
    })
      .then(this._handleHttpErrors)
      .then((response) => response.json())
      .then((response) => {
        // console.log('addIceCandidate ok:' + response);
      })
      .catch((error) => this.onError('addIceCandidate ' + error));
  };

  /*
   * RTCPeerConnection AddTrack callback
   */
  WebRtcStreamer.prototype.onAddStream = function(event) {
    // console.log('Remote track added:' + JSON.stringify(event));

    this.videoElement.srcObject = event.stream;
    var promise = this.videoElement.play();
    if (promise !== undefined) {
      var bind = this;
      promise.catch(function(error) {
        // console.warn('error:' + error);
        bind.videoElement.setAttribute('controls', true);
      });
    }
  };

  /*
   * AJAX /call callback
   */
  WebRtcStreamer.prototype.onReceiveCall = function(dataJson) {
    var bind = this;
    // console.log('offer: ' + JSON.stringify(dataJson));
    var descr = new RTCSessionDescription(dataJson);
    this.pc.setRemoteDescription(
      descr,
      function() {
        // console.log('setRemoteDescription ok');
        while (bind.earlyCandidates.length) {
          var candidate = bind.earlyCandidates.shift();
          bind.addIceCandidate.call(bind, bind.pc.peerid, candidate);
        }

        bind.getIceCandidate.call(bind);
      },
      function(error) {
        // console.log('setRemoteDescription error:' + JSON.stringify(error));
      }
    );
  };

  /*
   * AJAX /getIceCandidate callback
   */
  WebRtcStreamer.prototype.onReceiveCandidate = function(dataJson) {
    // console.log('candidate: ' + JSON.stringify(dataJson));
    if (dataJson) {
      for (var i = 0; i < dataJson.length; i++) {
        var candidate = new RTCIceCandidate(dataJson[i]);

        // console.log('Adding ICE candidate :' + JSON.stringify(candidate));
        this.pc.addIceCandidate(
          candidate,
          function() {
            // console.log('addIceCandidate OK');
          },
          function(error) {
            // console.log('addIceCandidate error:' + JSON.stringify(error));
          }
        );
      }
      this.pc.addIceCandidate();
    }
  };

  /*
   * AJAX callback for Error
   */
  WebRtcStreamer.prototype.onError = function(status) {
    // console.log('onError:' + status);
  };

  return WebRtcStreamer;
})();

if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
  module.exports = WebRtcStreamer;
else window.WebRtcStreamer = WebRtcStreamer;
